The essential objective of every implantable osteosynthesis device consists in the production of a clamping effect on the bony parts capable of guaranteeing an effective strengthening of the bone. For that purpose, all of the present devices for osteosynthesis are designed to possess, once implanted, a solidity and a rigidity which make it possible to guarantee the production of a perfect clamping effect. However, it turns out that in order to satisfy this objective, all of the solutions proposed have led to the design of osteosynthesis devices whose implantation requires a long and complex operational procedure and considerable ancillary instrumentation.
Thus, for example, in the context of osteosynthesis of the sternum in particular for the purpose of the closure of a sternotomy, currently used equipment consists of so-called COTREL-DUBOUSSET clamps comprising a first hook fixed to a threaded bar, a second hook designed to slide in the direction of the fixed hook, and means for blocking translational and rotational movement of this second hook comprising a screw nut/lock nut system and a locking screw introduced into the base of said second hook.
Although the clinical experiments demonstrated the reliability of this equipment which makes it possible to obtain good bone strengthening, the operating procedure for the implantation of the latter proves, on the other hand, to be relatively complex and difficult. In fact, this implantation requires the use of an adjustable clamp designed to ensure the sliding of the movable hook until the hooks are subject to compression, then while maintaining this compression, requires the blocking of the movable hook be ensured in the first place by means of the screw nut/lock nut system, and in the second place by means of the locking screw. Subsequently, the surplus bar must be cut by means of a wire cutter, and the head of the locking screw must also be cut so that it does not project.
In practice, it turns out that the implantation of two or three clamps, necessary for the osteosynthesis of the sternum requires a not inconsiderable period of time of about a quarter of an hour. Furthermore, it should be noted that such clamps are not completely reliable owing to the fact that the locking screw cannot guarantee absolutely the blocking of the rotation of the movable hook.